A Reader Writes, asking, [sic] “to increase the shelf life of chocolates (assorted or filled with fresh cream/milk) what preservatives to use?” In general, I don’t like to recommend using preservatives, but there are many techniques that can be used to increase shelf life without using artificial preservatives ...

The shelf life of chocolates (filled confections) at room temperature is governed by what is called the “water activity level.” When chocolates go bad, what is happening is that the dairy product(s) used to make the ganache go sour and/or turn moldy. We’ve all seen this happen in our refrigerators at one time or another, but it’s something else to see the inside of a piece of chocolate turn into a biology project.

What happens is that oxygen—which can be found in the ganache as well as permeating the chocolate shell—promotes the growth of bacteria in the dairy component of the ganache. The ways to improve shelf life (keep the bacteria from growing) include reducing the amount of dairy ingredients in the ganache, reduce the amount of oxygen in the ganache, and/or use preservatives either natural or artificial.

In many instances reducing the amount of dairy (butter, milk, cream) in the ganache is not an option, but one thing that can be done is boil already pasteurized milk or cream. This will kill some additional bacteria but may introduce a flavor of cooked milk (caramelly flavors) that are unwanted.

There are several ways to reduce the amount of oxygen getting to the filling.

The easiest is simply to make the coating or shells very thick. The chocolate shell hinders oxygen transfer thereby increasing shelf life. This does has the downside of completely changing the texture of the piece, which is probably to be avoided. Another way to do this is to mix the ganache in a special mixer under vacuum. As the chocolate and dairy ingredients are mixed together, because of the vacuum, no oxygen is incorporated into the mix. If you don’t have one of these special mixers (they are expensive) you can use a tall thin container and a stick blender (just don’t break the surface with the blender). This will give you a great emulsion without incorporating too much air into the mix.

Once you’ve taken a look at the dairy component and how to reduce oxygen content of the ganache, the next thing to look at is preservatives. There are a number of natural preservatives used in chocolate making that just happen to be types of sugar; sorbitol and trimoline. By using either of these two sugars you can reduce the dairy component of what you’re making while still retaining the degree of moistness you’re looking for. Many books on chocolate discuss how to adjust your recipes as you usually can’t add more than up to 10% of one of these ingredients.

Previous Questions and Answers:

1. Sometimes when I bake chocolate biscotti, even with thorough twice baking to remove all the moisture, then sealing in airtight clear packaging, the surface of the cookie starts to gray or bloom. There's no butter or oil in the recipe, and we're not talking chocolate coating here. What causes this, and what can I do to eliminate it?
   Posted by  on  02/07  at  06:13 PM
2. When making confections with my favorite imported chocolate, then packaging them in 'bulk' bags, the surface gets slightly marred by 'nicking' caused by the edges bumbing against each other during shipping. How can I get a harder, more durable 'set' without panning or adding any laquer type components?
   Posted by  on  02/07  at  06:16 PM
3. Karen: As near as I know, there is nothing you can do to harden the surface of the confections without panning and/or adding some sort of hard surface coating -- other than changing the way you package the goods. As long as they are free to move against each other, they will bump together during handling, especially shipping, causing the surface damage you're talking about. Is there a way to bulk pack in single layers? You could put a layer down (e.g., in a box) make sure the layer is tight so things won't move, put a candy pad on top of that, add another layer, etc. The pressure from the candy pads will keep things from jostling. Of course, this does raise the cost of labor and packaging, which is what you're probably trying to avoid by bulk packing. :: Clay
   Posted by  on  02/08  at  09:01 AM
4. Karen: As for the biscotti issue, I am not a knowledgeable baker so I can't help you there; if there was a chocolate coating on the biscotti I'd be able to start pointing you in the right direction What occurs to me is that there still might be some residual moisture in the biscotti that is condensing on to the surface and to make sure that the biscotti is completely cooled before packing. For an experiment, if you have one of the silia gel packets that come in some foods, add one of those to the package and see if you get the same thing to happen. If not, it's a moisture issue. I am a member of the Pastry and Baking forum on eGullet (http://www.egullet.com -- registration required), and this would be a great place to ask this question and get a more definitive answer. You should plan to post your recipe, too, so the bakers on the forum will be able to respond better. : Clay
   Posted by  on  02/08  at  09:06 AM
5. I was very interested in your information about using sorbitol and trimoline to increse shelf life of filled chocolates. I would like to know what books will help in explaining how to adjust recipes to accommodate these. Also, how long will this increase shelf life for? :: Maria; The best book I have seen on the subject is Jean-Pierre Wybauw's book, Fine Chocolate, Great Experiences. If you don't have a copy, get one. The answer to your latter question is really about what called water activity level. The more water in your chocolate (i.e., from cream/butter in the ganache) the shorter the shelf life. Sorbitol/Trimoline can help extend the shelf life but the actual time depends on water activity level. J-P W's book goes over these issues in great detail. :: Clay
   Posted by  on  10/12  at  06:35 AM
6. Hello, Could you please advise me "what is the correct transport/storage temperature/relative humidity range for chocolate covered macadamias). Is the chocolate going to be affected and how if, for example, the temperature of the chocolate when it arrives at the factory is 10 degreesC and there is visible condensation between the packaging and the product? Will this cause "blooming" of the chocolate? Will the shelf life of the product be affected? We suggest 14-20 degrees for storage/transport, however we have problems due to the transport conditions of our sucontractors' trucks and have concerns for the long term product quality. Thank you, Mariana
   Posted by  on  11/13  at  10:45 PM
7. I was wondering if you could tell me where I could get a recipe on how to make chocolate truffles that could be packaged and sold.

   :: Jeremy
   In a previous post I mention a fabulous book, Fine Chocolate, Great Experiences 
   by Jean-Pierre Wybauw. This is the book to get if you want to want to start experimenting
   with recipes to package and sell.
   
   :: Clay
   

   Posted by  on  11/29  at  06:30 PM
8. I am adoctor and have phd in food haygine please Iwant asking you about how to protect fresh cream from souring or from sparting water from fresh cream during transportation by any additives and it must be safe (Iwant binding fresh cream with its water content. the second Iwant another additives to keep bascuit dry and another to keep it not dry for my researsh .

   :: Dr Kater
   These questions are beyond my field of expertise.
   
   :: Clay 

   Posted by  on  03/10  at  05:35 AM
9. Hi, I love Hershey Bars, what is the best way to store them so they do not go soft in the summer heat? I am not wild about keeping them in the refrigerator, but I will if I have to do so. Thank you.

   :: Peter
   1) Buy them only when you need to -- let the store do all the work of 
   keeping them fresh. I know they are cheaper in bulk but it does 
   solve the storage problem.
   2) If you have an air conditioner in at least one room, keep it set to
   below 80. If you don't have an air conditioner, and chocolate is that 
   important to you, buy an air conditioner.
   3) There's nothing really wrong with storing them in the fridge, just 
   let them warm up a little first before you open the wrapper.
   
   :: Clay

   Posted by Stuart Joseph  on  08/24  at  03:18 PM
10. hi can u please tell me how to make liquer chocolate centres. i had come across a recipie on the net, which talked about crystallizing sugar to a particular temp n then adding liquer,so that a crystal is formed. this to be then filled in praline......but god that page could not be printed n i hv lost the bookmark. thankyou kavita.
    Posted by  on  01/08  at  07:52 AM